Biosynthetic-Studies on Tajixanthone and Shamixanthone, Polyketide Hemiterpenoid Metabolites of Aspergillus variecolor

Ahmed, S. A.; Bardshiri, Esfandiar; McIntyre, C. Rupert; Simpson, Trey

doi:10.1071/ch9920249

Cited by 42 publications

(39 citation statements)

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“…3. In agreement with this, previous studies have reported arugosins to be precursors for emericellin (10) and shamixanthones (11) and (12) (Ahmed et al, 1992;Kralj et al, 2006;Márquez-Fernández et al, 2007), but have not established a genetic link to mpdG.…”

Section: Mdpg Is Involved In the Biosynthesis Of Arugosinssupporting

confidence: 70%

A genome-wide polyketide synthase deletion library uncovers novel genetic links to polyketides and meroterpenoids in Aspergillus nidulans

Nielsen¹,

Nielsen²,

Rank³

et al. 2011

FEMS Microbiology Letters

106

114

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Fungi possess an advanced secondary metabolism that is regulated and coordinated in a complex manner depending on environmental challenges. To understand this complexity, a holistic approach is necessary. We initiated such an analysis in the important model fungus Aspergillus nidulans by systematically deleting all 32 individual genes encoding polyketide synthases. Wild-type and all mutant strains were challenged on different complex media to provoke induction of the secondary metabolism. Screening of the mutant library revealed direct genetic links to two austinol meroterpenoids and expanded the current understanding of the biosynthetic pathways leading to arugosins and violaceols. We expect that the library will be an important resource towards a systemic understanding of polyketide production in A. nidulans.

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Section: Mdpg Is Involved In the Biosynthesis Of Arugosinssupporting

confidence: 70%

A genome-wide polyketide synthase deletion library uncovers novel genetic links to polyketides and meroterpenoids in Aspergillus nidulans

Nielsen¹,

Nielsen²,

Rank³

et al. 2011

FEMS Microbiology Letters

106

114

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“…Numerous polyhydroxy anthraquinones, including emodin, versicolorone, tajixanthone, and 1,3,6,8-tetrahydroxyanthraquinone, have been isolated from various Aspergillus species as secondary metabolites (1,8,43,46). All of these materials have similar chelated and phenolic hydroxyl resonances, as well as aromatic proton resonances.…”

Section: Resultsmentioning

confidence: 99%

Isolation and Characterization of Sexual Spore Pigments from Aspergillus nidulans

Brown

Salvo

1994

Appl Environ Microbiol

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The homothallic ascomycete AspergiUlus nidulans produces two types of pigmented spores: conidia and ascospores. The synthesis and localization of the spore pigments is developmentally regulated and occurs in specialized cell types. On the basis of spectroscopic evidence, we propose that the major ascospore pigment of A. nidulans (ascoquinone A) is a novel dimeric hydroxylated anthraquinone. The structure of ascoquinone A, as well as a comparison to model compounds, suggests that it is the product of a polyketide synthase. Previous studies have revealed that the conidial pigments from A. nidulans and a related Aspergillus species (A. parasiticus) also appear to be produced via polymerization of polyketide precursors (D. W. Brown, F. M.

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“…Here, we have shown that A. nidulans produces emericellin, shamixanthone, dehydroaustinol, and ergosterol peroxide during development in solidphase medium and that CfwA/NpgA is needed for the production of these compounds. Based on chemical structure and xanthone biosynthesis in A. variecolor (3,4), the xanthone emericellin can be synthesized from an anthrone precursor through a pathway involving at least one PKS. Shamixhantone may be formed by cyclization of one of the emericellin isoprenylated chains.…”

Section: Discussionmentioning

confidence: 99%

Phosphopantetheinyl Transferase CfwA/NpgA Is Required for Aspergillus nidulans Secondary Metabolism and Asexual Development

et al. 2007

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Polyketide synthases (PKSs) and/or nonribosomal peptide synthetases (NRPSs) are central components of secondary metabolism in bacteria, plants, and fungi. In filamentous fungi, diverse PKSs and NRPSs participate in the biosynthesis of secondary metabolites such as pigments, antibiotics, siderophores, and mycotoxins. However, many secondary metabolites as well as the enzymes involved in their production are yet to be discovered. Both PKSs and NRPSs require activation by enzyme members of the 4-phosphopantetheinyl transferase (PPTase) family. Here, we report the isolation and characterization of Aspergillus nidulans strains carrying conditional (cfwA2) and null (⌬cfwA) mutant alleles of the cfwA gene, encoding an essential PPTase. We identify the polyketides shamixanthone, emericellin, and dehydroaustinol as well as the sterols ergosterol, peroxiergosterol, and cerevisterol in extracts from A. nidulans large-scale cultures. The PPTase CfwA/NpgA was required for the production of these polyketide compounds but dispensable for ergosterol and cerevisterol and for fatty acid biosynthesis. The asexual sporulation defects of cfwA, ⌬fluG, and ⌬tmpA mutants were not rescued by the cfwA-dependent compounds identified here. However, a cfwA2 mutation enhanced the sporulation defects of both ⌬tmpA and ⌬fluG single mutants, suggesting that unidentified CfwA-dependent PKSs and/or NRPSs are involved in the production of hitherto-unknown compounds required for sporulation. Our results expand the number of known and predicted secondary metabolites requiring CfwA/NpgA for their biosynthesis and, together with the phylogenetic analysis of fungal PPTases, suggest that a single PPTase is responsible for the activation of all PKSs and NRPSs in A. nidulans.Filamentous fungi represent a rich and diverse source of bioactive compounds derived from secondary metabolism. Indeed, many positive and negative effects that fungi have on human activity are mediated by secondary metabolites such as antibiotics and other pharmaceutical drugs, mycotoxins, or pathogen virulence factors (22, 30, 54-56, 60, 66). In contrast to primary metabolism, common to most living organisms, secondary metabolism is not essential for the immediate survival of the producing organism. Furthermore, different taxonomic groups produce different types of secondary metabolites.Despite their large chemical diversity, secondary metabolites can be grouped according to their primary metabolism precursors. Acetyl coenzyme A, shikimate, and amino acids are major secondary metabolite building units. Acetyl coenzyme A is used to produce terpenoids, steroids, carotenoids, and polyketides.

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Biosynthetic-Studies on Tajixanthone and Shamixanthone, Polyketide Hemiterpenoid Metabolites of Aspergillus variecolor

Cited by 42 publications

References 0 publications

A genome-wide polyketide synthase deletion library uncovers novel genetic links to polyketides and meroterpenoids in Aspergillus nidulans

A genome-wide polyketide synthase deletion library uncovers novel genetic links to polyketides and meroterpenoids in Aspergillus nidulans

Isolation and Characterization of Sexual Spore Pigments from Aspergillus nidulans

Phosphopantetheinyl Transferase CfwA/NpgA Is Required for Aspergillus nidulans Secondary Metabolism and Asexual Development

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